1. Technical Field
The present disclosure relates to a buck-boost converter and a control circuit thereof, in particular, to a buck-boost converter and a control circuit thereof which can reduce switching loss.
2. Description of Related Art
In a traditional buck-boost converter, a switching regulator is configured to operate among a boost mode, a buck mode, and a buck-boost mode in turn so as to convert an input voltage into a required output voltage. The switching regulator includes four power switches. When the switching regulator operates in the boost mode, only two of the four power switches are turned on alternatively. When the switching regulator operates in the buck mode, the other two power switches are turned on alternatively.
When the input voltage approximates to the output voltage, the traditional switching regulator operates in the buck-boost mode. In the buck-boost mode, when the input voltage is higher than the output voltage, the buck-boost converter operates in the buck mode; and when the input voltage is lower than the output voltage, the buck-boost converter operates in the boost mode. Due the input voltage being close to the output voltage, the four power switches are turned on or turned off alternatively and frequently, thereby increasing switching loss of the whole circuit and reducing the conversion efficiency of the buck-boost converter.
Therefore, reducing the switching loss of the whole circuit would improve the conversion efficiency of the buck-boost converter.